Inventors: Ryan P. Semple and Robert C. DeLong FIELD OF THE INVENTION

[0001] The field of the invention is bearing sleeves that are secured to a rotating shaft in equipment used in subterranean or subsea locations and more particularly where the sleeve is secured to the shaft without a keyway.

BACKGROUND OF THE INVENTION

[0002] In abrasive applications such as electric submersible pumps a sleeve is used to rotate with the shaft of a multistage pump inside a bushing. To handle the abrasive particles the sleeve and the bushing are frequently made of tungsten carbide. In the past the way the sleeve was attached to the shaft was to put a keyway in the sleeve and in the shaft and line up the keyways and insert a key in the keyway that spanned the shaft and the sleeve. In operation under torque loading, the shaft would flex so that one part of the sleeve was rotated to a small degree with respect to another part generally at the opposite end of the sleeve. The keyway by its nature required a portion of the wall removed and became a location of stress concentration. Add to that the brittle nature of carbide and the result was that there were cracks and failures in the sleeve.

[0003] One solution for this problem was to use a keyless connection between the shaft and the sleeve as illustrated in USP 7,182,584 and shown in FIGS. 4 and 5. Here the sleeve 98 came with depressions 108 and the retainer was fixed to the shaft in an undisclosed manner and had protrusions 106 that registered with depressions 108 in an effort to ensure that the shaft rotated with the sleeve 98. While somewhat schematic, FIG. 2 shows journal bearings 42 that seem to have the retaining rings held fast by snap rings that are not identified with a number.

[0004] Other art relating generally to shafts, sleeves and the application of springs to such designs are USP: 6,725,937 and 6,956,310 and US Publications 2005/0109515 and 2010/0008796.

[0005] The present invention seeks to mount the sleeve to the shaft without a keyway and form the engagement for torque transfer in a manner that allows slippage from over-torque with an ability to recover and obtain another grip. The torque transfer uses preferably rounded extending shapes from one of the retaining ring or the sleeve while making most of the mating surfaces flat and conducive to relative rotation when an over-torque situation arises. The opposed retainer rings are made of a mild steel material and keyed against rotation to the shaft but are also preferably biased axially by spring force that promotes contact but allows recovery from relative rotation after an over-torque occurrence passes. These and other aspects of the present invention will be more readily understood by those skilled in the art from a review of the detailed description of the preferred embodiment and the associated drawings while understanding that the full scope of the invention is to be determined by the appended claims.

SUMMARY OF THE INVENTION

[0006] A sleeve is retained to a shaft without the use of a keyway through at least one end connection that has a preferably flat face with one or more projections from the flat face. Rounded projections are preferred. The projections go into shape matching depressions on the sleeve. Alternatively the sleeve can have the projections and the end retainer can have the depressions. The end retainer is spring loaded for axial deflection in the event of an over-torque. If that happens there is planned for slippage until the condition is alleviated at which point the spring bias is able to again match a projection to a depression for continuing tandem driving of the shaft and the sleeve. The sleeve is preferably carbide and resides in a carbide bushing. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] FIG. 1 is an assembly of an electric submersible pump showing the bushing locations where the keyless sleeve will be located;

[0008] FIG. 2 is a closer in view of FIG. 1 showing the mounting of the keyless sleeve inside the bushings and the end bias details;

[0009] FIGS. 3-5 show alternative grip designs for the biased retaining ring; and

[0010] FIG. 6 is an alternative retaining element to the plug shown in FIG. 5. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0011 ] FIG. 1 shows a multistage electric submersible pump 10 with a shaft 12 extending through a plurality of diffusers 14.Each stage diffuser 14 has an impeller 16 that is fixed to the shaft 12 with a wedge ring (taper lock) retainer 18. Each stage has a carbide bushing 20 in its diffuser 14. The intake 22 is at the lower end and the discharge 24 is at the upper end.

[0012] FIG. 2 shows a close up view of FIG. 1 showing greater detail of two of the illustrated stages. A keyless carbide sleeve 26 is located within the busing 20 and is secured to the shaft with end rings 28 and 30. While opposed end rings 28 and 30 are shown it is possible to also use one located on one end with a flat and stationary travel stop on the opposite side. The end rings are preferably mild steel and have internal keyways to be secured rotationally to the shaft 12 using keys 32 and 34 respectively that are lodged in a continuous keyway 36 on the shaft 12. End ring 28 is axially retained by keyed sleeve 38 that has an end recess 40 that holds a biasing member 42 such as a coiled spring, a wave spring or a stack of Belleville washers, for example to maintain an axial force against the end ring 28. On the opposite side of the sleeve 26 a flanged spring retainer 44 is supported from the wedge ring retainer 18 and has an end recess 46 to hold a biasing member 48 similar to biasing member 42 against the end ring 30 that also has an end recess or one or more counterbores 50 to contain the biasing member 48. End ring 28 has an end recess or one or more counterbores 52 to contain the biasing member 42.

[0013] Preferably the sleeve 26 has flat ends 54 and 56 that have depressions 58 and 60 respectively. The projections that register with these depressions are best seen in FIGS. 3-6. Since the carbide is fairly brittle it is just simpler to put the projection in the end rings 28 or 30 rather than in the sleeve 26. In FIG. 3 the end ring 28 is illustrated and the description is applicable to end ring 30 as well. There is a flat surface 62 that goes against flat surface 54 of the sleeve 26. In the FIG. 6 embodiment there are rounded projections 64, 66, 68 and 70. Although four are shown the amount can be higher or lower. The projections 64, 66, 68 and 70 can be retained spheres or an elongated object with a rounded extending end and a way to fasten a body in a bore into the ring 28 using a thread or a snap ring or an equivalent fastener or adhesive or an interference fit or the like. FIG. 4 is similar to FIG. 3 except the rounded projections 64, 66, 68 and 70 are cast in place into the end ring such as 28. In FIG. 5 threaded plugs with rounded heads can be used for the projections 64, 66, 68 and 70. FIG. 6 illustrates that the projecting portion need not be only arcuate or hemispherical but can have blunter shapes that involve sloping sides such as 72.

[0014] It should be notes that above a predetermined torque from the shaft 12 through key 32 or 34 and into keyway 74 there will be relative rotation of the end ring such as 28 or 30 with respect to the sleeve 26 which will cause the projections 64, 66, 68 and 70 to be driven out from matching depressions such as 58 and 60. As this happens the projections 64, 66, 68 and 70 slide on flat ends 54 and 56 of the sleeve 26 while the springs 42 and 48 are compressed to enable relative rotation or slippage until an over torque situation is alleviated and the springs are strong enough to hold the projections 64, 66, 68 and 70 to the mating depressions such as 58 and 60. It should be noted that as slippage occurs the flat surface 62 is out of contact with the sleeve 26 end surfaces 58 or 60.

[0015] Those skilled in the art will appreciate that the keyless retention system described above has the advantages of a configuration that enables a clutching feature in the event of an over-torque. The end rings are axially movable so that relative rotation with respect to the sleeve can selectively take place with the ability to reconnect to the sleeve 26 using the force of the bias of the springs 42 or 48.

[0016] The above description is illustrative of the preferred embodiment and many modifications may be made by those skilled in the art without departing from the invention whose scope is to be determined from the literal and equivalent scope of the claims below.